Multiple-wire cable for high-frequency telephony and telegraphy



Nov. 27, 1923. 1,475,878

' L. RELLSTAB v MULTIPLE WIRE CABLE FOR HIGH FREQUENCY TELEPHONY AND TELEGRAPHY Filed March 6, 1925 aw/M Jud? @ZZSZTRZ Patented Nov. 27, 1923.

UNITED STATES 1,475,878 PATENT OFFICE.

LUIDWIG RELLSTAB, OF BERLIN-NIKOLASSEE, GERMANY, ASSIGNOR TO NAAMLOOZE VENNOOTSCHAP DE NEDERLANDSCHE THERMIO-TELEPHOON-MAATSCHAPPIJ, OF UTRECHT, NETHERLANDS, A CORPORATION OF THE NETHERLANDS.

MULTIPLE-WIRE CABLE FOR, HIGH-FREQUENCY TELEPHONY AND TELEGRAPHY! Application filed March 6, 1923.

To aZZw/rom it may concern:

Be it known that I, LUDWIG RELLSTAB, a citizen of Germany, and a resident of Berlin-Nikolassee, Germany, have invented certain new and useful Improvements in Multiple-Wire Cables for High-Frequency Telephony and Telegraphy, of which the following is a specification.

My invention relates to improvements in multiple-wire cables for high-frequency telephony and telegraphy. As is known to those skilled in the art in high-frequency telephony currents of very high frequency, such for example as 100,000 oscillations per second, are used, and the amplitudes of the said currents are affected by the oscillations of the sounds being transmitted, which oscillations have comparatively low frequen cies. Therefore, when using a multiple wire cable comprising double conductors, in a double conductor several currents of different frequencies are superimposed.

If the difference of the said frequencies is small the communication by one circuit is interfered with by induction caused by the currents in the other, which effect is particularly conspicuous and troublesome in case of high frequencies. For removing this objection currents of widely different frequen cies might be employed, which, however, is not feasible in multiple-wire cables for the reason that very high and very low frequencies would be necessary, the number of the frequencies being very high, because it is composed of the superimposed frequencies of each double-conductor and the number of the double conductors.

The object of the improvements is to provide a cable in which the said induction is materially reduced without using very high or very low frequencies, and with this object in view I combine several double conductors into adjacent bundles, and I enclose each bundle in a conductive sheath consisting for example of tin-foil. The conductive sheath of the individual bundles provides an electrostatic and electrodynamic screen for the double wires confined therein; Therefore by combining a suitable number of double conductors into adjacent bundles the number of the frequencies is reduced, and the difference of the frequencies is increased to such an extent that the currents in one conductor do Serial No. 623,125.

not interfere with the communication by another conductor.

By the conductive sheath the capacity of each double conductor is increased, because by placing a conductive surface adjacent to a double conductor the relative capacity of both conductors is increased. Another object of the invention is to reduce the in crease of the capacity as far as possible. With. this object in view I place insulating material between the double conductors combined into bundles and the conductive sheath. Thereby the distance of the bundle of double conductors and the conductive sheath is increased and the capacity reduced. I

In order that my invention be more clearly understood an example embodying the same has been illustrated in the accompanying drawing showing a cross-section of the improved cable.

The individual conductors of the cable consist of very thin wires insulated by means of lacquer, two of the said wires being twisted together and insulated from each other by a sheath of paper 6 and an air space. In the example shown in the figure six double wires a, a are combined into a bundle coated circumferentially with a sheath 0 of tin-foil, aluminium-foil, paper coated with conducting material, and the like. Between the conductive sheath 0 and the bundle of double wires a, or, there is an insulation 03 consisting for example of paper. As shown seven bundles are combined into a multiple-wire cable having a lead sheath 6 as is known in the art.

By reason of the electrostatic and electrodynamic action of the metallic sheaths c of the individual bundles of double conductors a, 00 within the same bundle currents of widely different frequencies can be used and the communication by one wire is not interfered with by induction from another. The increase of the relative capacity of the individual wires of each double conductor a, a by the metallic sheath 0 is immaterial, because the said sheath is held at a suflicient distance away from the double conductors by the paper insulation d.

The cable is useful also in high frequency telegraphy.

I am aware that it has heretofore been proposed to enclose the individual double conductors of a cable each Within a conductive sheath, or to encloseconcenteric layers of double conductors Within conductive sheaths disposed concentrically of the sheath of the cable. However these constructions are not suitable for the object aimed at by my invention and in a multiple-Wire cable for high frequency telephony, because to coat each individual double Wire results in an objectionable Waste of conductive sheath material, and by distributing the double conductors over concentric layers Widely diflerent groups of double conductors are produced,because the number of the double Wiresin the successive layers increases from the center to the circumference of the cable.

In multiple-Wire cables for high frequency telephony uniform groups of double conductors are preferred.

The following example Will illustrate this. It may beassumed that by each double coir ductor three communications are simultaneously transmitted. As for speaking in opposite directions difierent frequencies are des1rable,s1X different frequencies are r quired for each doubleconductor, or 126' cies Where it is desired to avoid an accidental coincidence. If, hovvever,the bundles contain different numbers of conductors, as is the case Where the Wires are disposed in concentric layers, there wouldhardly be placed onebeside theother, each bundle being 1 separately enclosed ina conductive sheatlnt each bundle comprising a plurality of don ble conductors.

2. A multiple-Wire double conductor cable, comprising a plurality of bundles placed one beside the other, each bundle being 1 separately enclosed in a conductive sheath,

each bundle comprising a plurality of double conductors and insulating material between the double conductors and theconduct-ive sheaths.

In testimony whereof I hereunto affix my signature inthe presence'of two Witnesses.

LUDWIG RELLSTAB.

Witnesses G. HoLTzEnAN, MARGARETE OTTE. 

